Since I don't know the exact novel, I can't say for sure. But usually, there would be the hero who comes from another world. There might also be characters who help or oppose the hero in the new world.
In an 'isekai kara kita yuusha novel', the main character is the hero from another world, of course. There could be a princess or a wizard who becomes the hero's ally. Maybe there is also a powerful villain who wants to stop the hero from achieving his goals in the new world. The relationships between these characters would drive the plot forward.
The main character in the 'isekai kara kita yuusha novel' is the hero who has journeyed from another world. There may be side characters like local villagers who the hero befriends and protects. There could be a mentor figure, perhaps an old sage, who teaches the hero about the new world's magic or lore. And then there would be antagonists, like a dark lord or a group of bandits, that the hero has to face and overcome in his adventures.
Chapter 625, "An Anonymous Corpse Found in the Wilderness?!", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event.
Chapter 820, "He’s actually even harder to coax than Buchen!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Today, he was particularly cautious with his eating, even sipping his...
Chapter 909, "Hexin Sanatorium", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Li looked at him, as if recalling something.
Chapter 621, "What Makes You Think I Would Save You?", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from The two walked for a long time before they reached a point where the...
Chapter 673, "Don't You Think They Look Alike?", is the clearest early answer because it turns Don's situation into a concrete plot event. It opens with Jiang Li smiled, but her gaze thoroughly sized up Shu Yan. and closes on The infinite rebirth that had troubled him was broken, and his....
A practical answer is Chapter 14, because it turns the idea into a concrete scene. The chapter opens with Lin Manru had a rare good night's sleep., adds pressure through The young, vibrant life was buried amid the vast expanse of white, along..., and ends on But clearly, Lin Manru was unable to.
Chapter 660, "Includes Meals and Accommodation?", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. It opens with My point exactly," Jiang Li said, "I'll pay off the over twelve...
Chapter 807, "If You Dare, Go Complain Now", is the clearest early answer because it turns Jiang Bufan's situation into a concrete plot event. It opens with Jiang Bufan had barely eaten dinner, having spent the whole day being...
Chapter 810, "I'm Waiting for Death", is the clearest early answer because the violence around Seeing Jiang Buchen becomes final instead of hypothetical. A useful checkpoint is the way the scene starts with Jiang Buchen was about to go crazy from hunger.
Chapter 810, "I'm Waiting for Death", is the clearest early answer because the violence around Jiang Buchen becomes final instead of hypothetical. The chapter gives readers a real answer by opening on Jiang Buchen was about to go crazy from hunger.